I. Field of the Invention
This invention pertains to a method of adhering or bonding material to a rigid substrate and an article produced thereby, and particularly to a method and article wherein fabric is adhered to a thermoplastic substrate using vacuum molding techniques.
II. Prior Art and Other Considerations
Numerous commercial products are formed by adhering a fabric to a rigid substrate. Adhering the fabric to a nonplanar substrate is quite difficult especially when it is required that the adhered fabric have the same profile or contour as the nonplanar substrate. One good example of such a product is an interior door panel incorporated into a vehicle such as an automobiIe.
When finally assembled, the contour of a vehicular interior door panel is generally fairly intricate for both functional and aesthetic reasons. Typically, the interior door panel contours have sizeable functional protrusions (such as an armrest, for example) and ridges or depressions that enhance the decorative appearance of the door.
It is generally desired that all contour features associated with the interior door panel be comfortable to the touch and appealing to the eye, for which reasons each contour feature is generally covered with a layer of fabric. Conventional fabrication techniques have not afforded a method for easily but securely adhering a single piece of fabric onto a unitary interior door panel substrate of nonplanar contour. Consequently, interior panels are generally formed as a composite, i.e., by separately adhering fabric to each of a plurality of separately-formed door panel substrate sections and then securing the separately-formed door panel substrate sections to one another (as by affixing an armrest to an essentially planar panel section, for example).
In accordance with conventional techniques, a fabric having a suitable backing (such as vinyl, for example) is employed. The fabric is cut into a plurality of pieces, each fabric piece being appropriately sized in view of the particular panel substrate section to which it is to be adhered. Glue is applied to the fabric backing, and the glued fabric backing is placed over its corresponding panel substrate section. Once the fabric adheres to its corresponding panel substrate section, the section is affixed by fasteners or otherwise to other substrate sections which form the interior door panel structure. Often a trim material or the like is used to cover the points at which the affixed door sections boarder one another. Thus, numerous steps involving considerable amount of time and labor are required to produce an interior door panel.
Interior door panels are constructed as a composite rather than by adhering a single piece of fabric to a unitary interior door panel substrate in view of the extraordinary difficulty in gluing a single piece fabric to the complex contours of the substrate in a manner whereby the fabric closely clings to the substrate contour, particulary in crevices. Without the ability to properly glue the fabric, the contour of the fabric is somewhat haphazard and does not have the sharp definition of the substrate contour.
The use of a male mold (such as mold 20 in FIG. 1) has been proposed for vacuum molding techniques wherein it is desired to securely adhere a fabric onto onto a rigid nonplanar substrate. According to this proposal and as shown in FIG. 1A, a fabric 22 is first laminated to a thermoplastic substrate 24 using an adhesive. Both the fabric 22 and the substrate 24 must be capable of considerale dimensional elongation on the order of at least 60% to 70%. Fabrics having such elongative properties typically contain lycra and are relatively expensive. The fabric-laminated substrate is then heated so that substrate sags sufficiently as shown in FIG. 1B. The sagging temperature for substrates of the type suitable for an article such as a door panel are quite high. At such temperatures (generally in excess of 220.degree. F.) some types of fabrics are scorched. Scorched fabric does not have the aesthetic appeal suitable for vehicle interiors and the fiber texture is damaged.
Assuming that a substrate which sags at a lesser temperature (for example, a temperature on the order of 180.degree. F.) were usable, the finished product would nonetheless not be satisfactory. In this regard, FIG. 1C shows the placement of the sagging fabric-laminated substrate onto the male mold 20. As a vacuum is applied to vacuum holes 26 in the male mold 20, the vacuum affects the substrate for the shaping of the substrate but there is a tendency in the nonplanar corner regions for the fabric to separate from the substrate.
While thermoplastic vacuum molding techniques have been employed in the textile industry to give a three-dimensional shape to thermoformable, stretchable textile fabrics, such techniques cannot be used to securely adhere a fabric onto a rigid, nonplanar substrate for the production of an article such as an interior door panel incorporated into a vehicle such as an automobile. In this regard, U.S. Pat. No. 3,962,392 to Conner uses a thermoformable sheet plastic material as a barrier to air flow in a vacuum forming operation wherein a thermoformable textile fabric is drawn into a mold cavity. Although some interlock occurs between the fabric and the plastic to prevent the fabric from slipping on the plastic and loosing its shape, the fabric is taken off the plastic so that the fabric alone can be used as a component of an article of apparel.
In view of the foregoing, it is object of the present invention to provide a vacuum molding process wherein a single piece of material such as fabric is easily and securely adhered to a substrate and whereby the substrate is given a nonplanar configuration, and to provide an article produced by said process.
An advantage of the present invention is the provision of a process whereby a single piece of fabric is adhered to a nonplanar rigid substrate in a single adhering step.
Another advantage of the present invention is the provision of a process whereby a relatively inexpensive single piece of fabric is adhered to a nonplanar substrate.
Yet another advantage of the present invention is the provision of a process whereby a single piece of material is easily adhered to a rigid substrate in manner whereby the substrate is given a nonplanar contour which is closely replicated in the contour of the fabric adhered thereto.